The Boston mayor remembers his grandmother reverting to childlike behaviors when her children implored her to remember them. She did not recognize her children, or her grandchildren, or any of the family members who surrounded her in her home in Ireland in the last years of her life.

Walsh talked about his late grandmother, Mary Ann O’Malley, when he announced an Alzheimer’s initiative Friday that will make Boston the first major city to join the Alzheimer’s Workplace Alliance. The national group has nearly 2,000 companies and organizations that support employees with information on Alzheimer’s.

Through this membership, up to 17,000 city employees, from police to public housing workers, will be trained in the particular needs of people with dementia and how best to care for the estimated 10,000 Bostonians suffering from Alzheimer’s, Walsh said.

More than half of those suffering from the disease have not been diagnosed, said James Wessler, president of the Alzheimer’s Association of Massachusetts and New Hampshire.

Walsh talked about improving Alzheimer’s services in his inaugural address in January, promising to expand and better coordinate city services.

“What we have developed is a comprehensive plan to connect people to the resources they need,” Walsh said at a press conference at Boston Medical Center. “It’s a tough disease for a lot of family members.”

The alliance will not only help those with Alzheimer’s, but the estimated 30,000 family members in the city caring for those with the disease. Alzheimer’s caregivers can experience increased levels of depression and neglect their own health care, Wessler said.

“Too many caregivers try to do this alone, and we always say you cannot do Alzheimer’s disease alone,” Wessler said. “Alzheimer’s can literally overwhelm a family.”

Bernice Osborne-Pollard, who takes care of her mother with advanced Alzheimer’s in Dorchester, said it took her family eight years to seek professional help. It took her and her siblings years to come to terms with the disease and to openly discuss it with other family members.

But she hopes the city initiative will encourage others facing a similar challenge to ask for help.

“The more we talk about it, the more comfortable people are with it,” Osborne-Pollard said. “When my mother was diagnosed, the word caregiver wasn’t even really used.”

The number of people with Alzheimer’s nationwide is expected to grow 25 percent from now until 2025, as the baby boom generation ages into their 70s, Wessler said.

By 2050, the number of those suffering from the disease will grow threefold.

“If we want to talk about the quality of life in Boston, we have to reach out to these folks,” Walsh said. “We have to help them find the answers that they need, so they can address and deal with what’s going on in their family.”